U.S. patent application number 17/535148 was filed with the patent office on 2022-07-21 for lockable spinal implant.
The applicant listed for this patent is Howmedica Osteonics Corp.. Invention is credited to John E. Ashley, Walter Dean Gillespie, George A. Mansfield, III, David G. Matsuura, Philip J. Simpson.
Application Number | 20220226127 17/535148 |
Document ID | / |
Family ID | |
Filed Date | 2022-07-21 |
United States Patent
Application |
20220226127 |
Kind Code |
A1 |
Ashley; John E. ; et
al. |
July 21, 2022 |
Lockable Spinal Implant
Abstract
A spinal implant which is configured to be deployed between
adjacent vertebral bodies. The implant has at least one extendable
support element with a retracted configuration to facilitate
deployment of the implant and an extended configuration so as to
expand the implant and effectively distract the disc space,
stabilize the motion segments and eliminate pathologic spine
motion. The implant has a minimal dimension in its unexpanded state
that is smaller than the dimensions of the neuroforamen through
which it typically passes to be deployed within the intervertebral
space. The implant is provided with a locking system having a
plurality of linked locking elements that work in unison to lock
the implant in an extended configuration. Bone engaging anchors
also may be provided to ensure secure positioning.
Inventors: |
Ashley; John E.; (Danville,
CA) ; Simpson; Philip J.; (Escondido, CA) ;
Gillespie; Walter Dean; (San Diego, CA) ; Matsuura;
David G.; (Del Mar, CA) ; Mansfield, III; George
A.; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Howmedica Osteonics Corp. |
Mahwah |
NJ |
US |
|
|
Appl. No.: |
17/535148 |
Filed: |
November 24, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16504495 |
Jul 8, 2019 |
11191647 |
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17535148 |
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15377377 |
Dec 13, 2016 |
10342673 |
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16504495 |
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14644969 |
Mar 11, 2015 |
9545316 |
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15377377 |
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13843390 |
Mar 15, 2013 |
8992620 |
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14644969 |
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12787281 |
May 25, 2010 |
8696751 |
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13843390 |
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PCT/US2009/067446 |
Dec 10, 2009 |
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12787281 |
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12548260 |
Aug 26, 2009 |
8435296 |
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PCT/US2009/067446 |
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12380840 |
Mar 4, 2009 |
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12548260 |
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12072044 |
Feb 22, 2008 |
8932355 |
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12548260 |
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61201518 |
Dec 10, 2008 |
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International
Class: |
A61F 2/44 20060101
A61F002/44 |
Claims
1. A device for stabilizing a spine of a patient's body,
comprising: an expandable fusion implant adapted to be implanted
into an intervertebral space between a first vertebra and a second
vertebra of the spine, the implant including a first vertebral
engagement surface adapted to engage the first vertebra and an
opposing second vertebral engagement surface adapted to engage the
second vertebra, the implant being expandable by moving the first
vertebral engagement surface away from the second vertebral
engagement surface in a superior/inferior dimension such that the
height of the implant is increased; wherein, during expansion of
the implant, a member of the implant advances in a first direction
along a lateral dimension of the implant, the member advancing
along a ratcheting surface oriented orthogonally to the
superior/inferior dimension, the ratcheting surface resisting
movement of the member in a second direction opposite to the first
direction.
2. The device of claim 1, wherein the member restrains the first
and second bodies from moving back towards one another.
3. The device of claim 1, wherein the first vertebral engagement
surface is positioned on a first body of the implant, the second
vertebral engagement surface is positioned on a second body of the
implant, and the ratcheting surface is provided on the second
body.
4. The device of claim 3, wherein the ratcheting surface is defined
by an array of pointed teeth.
5. The device of claim 3, wherein the member is a pawl slidably
engaged along the ratcheting surface.
6. The device of claim 5, wherein the pawl is pivotably coupled to
the first body.
7. The device of claim 1, wherein the expansion of the implant
induces the advancement of the member in the first direction along
the ratcheting surface.
8. The device of claim 1, wherein the implant is expandable by
operation of at least one extendable support element of the
implant, the at least one extendable support element being driven
by fluid pressure.
9. The device of claim 8, wherein the at least one extendable
support element includes a piston slidably disposed within a
cylinder.
10. The device of claim 1, wherein the implant is expandable by
operation of a first extendable support element and a second
extendable support element spaced apart from one another in the
lateral dimension of the implant.
11. The device of claim 10, wherein the implant includes an
interior cavity positioned between the first and second extendable
support elements, the implant including at least one opening
extending through an outer surface of the implant to the interior
cavity so that graft material received within the interior cavity
can communicate with the intervertebral space.
12. The device of claim 1, wherein, during the expansion of the
implant, a second member advances in the lateral dimension along a
second ratcheting surface oriented orthogonally to the
superior/inferior dimension.
13. The device of claim 12, wherein, during the expansion of the
implant, the second member advances in the second direction
opposite to the first direction.
14. The device of claim 1, wherein the first and second directions
extend parallel to a longitudinal axis of the implant.
15. The device of claim 14, further comprising a second ratcheting
surface oriented orthogonally to the superior/inferior dimension,
wherein the ratcheting surface is positioned on a first lateral
side of the implant and the second ratcheting surface is positioned
on a second lateral side of the implant, the second lateral side
being opposite to the first lateral side across the longitudinal
axis of the implant.
16. The device of claim 1, wherein the implant is configured such
that an angle defined between the first vertebral engagement
surface and the second vertebral engagement surface varies during
the expansion of the implant.
17. A device for stabilizing a spine of a patient's body,
comprising: an expandable fusion implant adapted to be implanted
into an intervertebral space between a first vertebra and a second
vertebra of the spine, the implant including a first body adapted
to engage the first vertebra and an opposing second body adapted to
engage the second vertebra, the implant being expandable by moving
the first body away from the second body in a superior/inferior
dimension such that the height of the implant is increased;
wherein, during expansion of the implant, a member of the implant
advances in a lateral dimension along a set of ratcheting teeth
arranged in an elongated array extending orthogonally to the
superior/inferior dimension, the member restraining the first and
second bodies from moving back towards one another.
18. The device of claim 17, wherein, during the expansion of the
implant, a second member advances in the lateral dimension along a
second set of ratcheting teeth arranged in a second elongated array
extending orthogonally to the superior/inferior dimension.
19. The device of claim 17, wherein the elongated array of
ratcheting teeth extends parallel to a longitudinal axis of the
implant.
20. The device of claim 19, further comprising a second set of
ratcheting teeth arranged in a second elongated array extending
orthogonally to the superior/inferior dimension, wherein the
elongated array of ratcheting teeth is positioned on a first
lateral side of the implant and the second elongated array of
ratcheting teeth is positioned on a second lateral side of the
implant, the second lateral side being opposite to the first
lateral side across the longitudinal axis of the implant.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 16/504,495, filed Jul. 8, 2019, which is a
continuation of U.S. patent application Ser. No. 15/377,377, filed
Dec. 13, 2016, which is a continuation of U.S. patent application
Ser. No. 14/644,969, filed Mar. 11, 2015, which is a continuation
of U.S. patent application Ser. No. 13/843,390, filed on Mar. 15,
2013, which is a continuation-in-part of U.S. patent application
Ser. No. 12/787,281, filed on May 25, 2010, which is a
continuation-in-part of International Application No.
PCT/US2009/67446 filed Dec. 10, 2009, which is a continuation of
U.S. patent application Ser. No. 12/548,260, filed on Aug. 26,
2009. U.S. patent application Ser. No. 12/548,260 is a
continuation-in-part of U.S. patent application Ser. No.
12/072,044, filed on Feb. 22, 2008, and is a continuation-in-part
of U.S. patent application Ser. No. 12/380,840, filed on Mar. 4,
2009, which claims the benefit of the filing date of U.S.
Provisional Patent Application No. 61/201,518, filed on Dec. 10,
2008, the disclosures of all of which are hereby incorporated
herein by reference.
FIELD OF THE INVENTION
[0002] The invention relates to devices and methods for stabilizing
the vertebral motion segment. More specifically, the field of the
invention relates to an expandable spinal implant with locking
elements configured to lock the implant in an expanded
configuration within an intervertebral space to provide controlled
spinal correction in three dimensions for improved spinal
intervertebral body distraction and fusion.
BACKGROUND
[0003] A conventional spine cage or implant is characterized by a
kidney bean shaped body which is typically inserted posteriorly
through the neuroforamen of the distracted spine after a trial
implant creates a pathway. Existing devices for interbody
stabilization have important and significant limitations, including
inability to expand and distract the end plates or to fix the
device in place to prevent relative movement between the device and
an adjacent vertebral body. Current devices for interbody
stabilization include static spacers composed of titanium, PEEK,
and high performance thermoplastic polymer produced by VICTREX,
(Victrex USA Inc, 3A Caledon Court; Greenville, S.C. 29615), carbon
fiber, or resorbable polymers. Moreover, current interbody spacers
do not maintain interbody lordosis and can contribute to the
formation of a straight or even kyphotic segment and the clinical
problem of "flatback syndrome." Separation of vertebral end plates
increases space available for the neural elements, specifically the
neural foramen. Existing static cages do not reliably improve space
for the neural elements. Therefore, what is needed is a spinal
implant that will provide space for the neural elements posteriorly
between the vertebral bodies, or at least maintain the natural bone
contours to avoid neuropraxia (nerve stretch) or encroachment.
[0004] Conventional devices for intervertebral body stabilization
include poor interface between bone and the biomaterial of the
device. Conventional static interbody spacers form a weak interface
between bone and biomaterial. Although the surface of such implants
is typically provided with a series of ridges or coated with
hydroxyapetite, the ridges may be in parallel with applied
horizontal vectors or side-to-side motion. That is, the ridges or
coatings on the implant offer little resistance to movement applied
to either side of the end plates. Thus, nonunion is common in
allograft, titanium and polymer spacers, due to motion between the
implant and host bone.
SUMMARY OF THE DISCLOSURE
[0005] This invention is generally directed to a spinal implant for
insertion between superior and second vertebral end plates after
partial or total removal of a spinal disc. The spinal implant
embodying features of the invention has a contracted configuration
for easy installation between adjacent vertebral bodies and an
expanded configuration to support the vertebrae in a desirable
position. More specifically, the implant has a plurality of
inter-engagable elements which locks the implant in an expanded
configuration to hold the vertebral or joint sections in the
desired positions.
[0006] The invention is particularly directed to a spinal implant
suitable for placement between superior and interior vertebral
bodies. The spinal implant has a first member or top plate for
engaging an end of the superior vertebral body and a second member
or base for engaging an end of the inferior vertebral body and has
one or more extendable support elements preferably with one or more
top end plates that engage vertebral bodies in the expanded
configuration. The one or more extendable support elements have a
first contracted configuration to facilitate deployment of the
implant between the superior and inferior vertebral bodies and
safely past sensitive neural elements and a second or an extended
configuration to engage the end plates of the vertebral bodies. The
implant has a locking system with linked locking elements that
mechanically engage or interlock with the extendable support
element or the first member to lock the implant between the
superior and inferior vertebral bodies in an expanded
configuration.
[0007] The extendable support element(s) may be extended in a
variety of ways such as with fluid pressure, e.g. hydraulic fluid
or gas, by mechanical force, such as a threaded connection with a
rotating driving member or other suitable means. Fluidic
displacement is preferred. The extendable support element(s) are
disposed in cylinders which support and guide the extendable
support elements when they are extended. However, the locking
system is separate from the extendable support member and cylinder
receiving the supporter member, although the extending support
member may initiate the locking system and the support member and
cylinder may have lock support members attached thereto.
[0008] In one exemplary system, the spinal implant having features
of the invention comprises an inferior pressure applying member or
base with a first bone engaging surface, one or more extendable
support members cooperating with the base and a superior pressure
applying member such as a top end plate with a second bone engaging
surface that is coupled to the at least one extendable member. The
spinal implant preferably has a plurality of engaging locking
elements that are configured to independently lock one or more of
the extendable support members or pressure applying members in an
extended configuration to thereby provide desired disc height
between adjacent vertebrae.
[0009] The spinal implant or selectively expanding spine cage (SEC)
embodying features of the invention is particularly suitable for
posterior or transforaminal insertion between superior and inferior
vertebral end plates as described in copending applications Ser.
No. 11/535,432, filed Sep. 26, 2006, and Ser. No. 11/692,800, filed
Mar. 28, 2007. The implant has a contracted or unexpanded
configuration which allows easy deployment and is typically about
0.5 to about 1 cm in maximum short transverse dimension so as to
enable minimally invasive insertion posteriorly between vertebral
pedicles through a working space of approximately 1 cm in
diameter.
[0010] In one exemplary embodiment, the spinal implant for
placement between adjacent vertebral bodies as described above has
an upper locking member with stepped supporting surfaces on the
underside thereof and a lower locking member with stepped
supporting surfaces on the top side thereof which are configured to
engage the stepped supporting surface of the upper locking member
to lock the implant in an extended configuration. Extension of the
expandable members, such as bellows or pistons; or other
appropriately sized mechanisms, such as cams or screws, to raise
the superior pressure applying member increases longitudinal
spacing between the upper and lower locking members. Relative
motion, rotational or linear, between the upper and lower locking
members causes the stepped supporting surfaces of the lower locking
members and the stepped supporting surfaces of the upper locking
members to re-engage to fix the locking members in an increased
spaced apart relationship and thereby lock the implant in the
extended configuration.
[0011] Since the vertebral end plates are held together at one end
by a ligament much like a clamshell, as the implant expands against
the vertebral end plates, the amount of vertical expansion can be
adjusted to create the desired anterior/posterior correction
angle.
[0012] A minimally invasive downsized insertion tool, such as
described in the above referenced applications, both inserts the
unexpanded implant posteriorly and provides the hydraulic or
mechanical lines communicating with the interior of the implant.
The insertion tool may also provide a line for communicating the
liquid or slurry bone graft material into the intervertebral space
for subsequent fusion. Advantageously, hydraulic lines are small
size tubing to allow for high hydraulic pressure without danger of
the lines bursting.
[0013] Due to the mechanical advantage provided by a hydraulic
system or a proximally operated mechanical system, the implant has
minimized size and diameter in its unexpanded state that is smaller
than the diameter of a prepared neuroforamen. The implant thus can
be inserted transforaminally and engaged between the end plates of
the adjacent vertebra to effectively distract the intervertebral
area, restore space for neural elements, stabilize the motion
segment and eliminate pathologic segmental motion. The implant
enhances spine arthrodesis by creating a rigid spine segment.
[0014] The implant is preferably provided with a hollow interior to
enable a comparatively large quantity of bone growth conductive or
inductive agents to be contained therein that through openings
communicate directly to adjacent bone. Importantly, this results in
fixation forces greater than adjacent bone and soft tissue failure
forces. The implant can be used to promote fusion, and/or to
correct deformities such as scoliosis, kyphosis, and
spondylolisthesis.
[0015] The clinical goals of the implant and the method for its
insertion provide a minimally invasive risk of trauma to nerve
roots, reduce pain, improve function, and permit early mobilization
of the patient after fusion surgery. The fixation elements maintain
the implant in a desired position until healing (fusion or
arthrodesis) occurs. At this point, the implant is incorporated
inside bone and its role becomes quiescent.
[0016] Thus, a feature of the invention is that an implant can be
inserted posteriorly between vertebral pedicles in only a working
space of about 1/2 cm and then be expanded from about 100% to about
200%, typically about 160%, of its original insertion size and
locked in that position to provide a closely controlled full range
of permanent spinal correction in three dimensions. These and other
advantages of the invention will become more apparent from the
following detailed description and the accompanying exemplary
drawings.
[0017] In other embodiments of the invention, extendable, locking,
bone engaging anchors are provided to ensure that the implant is
positively engaged with the bone after insertion.
[0018] In one implementation, the present disclosure is directed to
a lockable, extendable spinal implant for placement between first
and second vertebral bodies. The implant includes: first and second
bone engaging members each having a surface configured to
respectively engage opposed first and second vertebral bodies;
extension means acting between the first and second bone engaging
members to control extension of the bone engaging members between
contracted and extended configurations; first and second fixed lock
members fixed to one of the first and second bone engaging members
and extending towards the opposite bone engaging member, the fixed
lock members being spaced apart and each having a fixed locking
surface; first and second moveable lock members captured between
the first and second bone engaging members for cooperation with the
fixed lock members, each moveable lock member having a moveable
locking surface configured to engage an opposed fixed locking
surface on one the fixed lock member to prevent contraction of the
extension means; a locking actuator configured to engage the
moveable locking surfaces with the fixed locking surfaces; and a
link member operatively connected between the first and second
moveable lock members to coordinate movement therebetween.
[0019] In another implementation, the present disclosure is
directed to a lockable, extendable spinal implant for placement
between first and second vertebral bodies. The implant includes:
first and second bone engaging members each having a surface
configured to respectively engage opposed first and second
vertebral bodies; first and second pistons disposed on one the bone
engaging member and cooperating with mating cylinders disposed on
the opposite bone engaging member, the pistons moveable between a
contracted configuration within the cylinders and an extended
configuration extending from the cylinders; first and second
arcuate, fixed lock members, each having a fixed locking surface,
mounted to one of the bone engaging members, each disposed around
one the piston, the fixed lock members extending towards the
opposite bone engaging member; first and second moveable lock
members, each formed around one the cylinder for cooperation with
the fixed lock members, each moveable lock member having a moveable
locking surface configured to engage an opposed fixed locking
surface on one the fixed lock member to prevent contraction of the
extension means; at least one biasing element acting on at least
one the moveable lock member to bias the member into engagement
with its associated fixed lock member; and a link member
operatively connected between the first and second moveable lock
members to coordinate movement therebetween and force the other
moveable lock member into engagement with its associated fixed
lock.
[0020] In still another implementation, the present disclosure is
directed to a lockable, extendable spinal implant for placement
between first and second vertebral bodies. The implant includes:
first and second bone engaging members each having a surface
configured to respectively engage opposed first and second
vertebral bodies; first and second pistons disposed on one the bone
engaging member and cooperating with mating cylinders disposed on
the opposite bone engaging member, the pistons moveable between a
contracted configuration within the cylinders and an extended
configuration extending from the cylinders; first and second
arcuate, fixed lock members, each having a fixed locking surface,
mounted to one of the bone engaging members, each disposed inside
one the piston, the fixed lock members extending towards the
opposite bone engaging member; first and second moveable lock
members, each formed inside one the cylinder for cooperation with
the fixed lock members, each moveable lock member having a moveable
locking surface configured to engage an opposed fixed locking
surface on one the fixed lock member to prevent contraction of the
extension means; at least one biasing element acting on at least
one the moveable lock member to bias the member into engagement
with its associated fixed lock member; and a link member
operatively connected between the first and second moveable lock
members to coordinate movement therebetween and force the other
moveable lock member into engagement with its associated fixed
lock.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] For the purpose of illustrating the invention, the drawings
show aspects of one or more embodiments of the invention. However,
it should be understood that the present invention is not limited
to the precise arrangements and instrumentalities shown in the
drawings, wherein:
[0022] FIG. 1 is a perspective view of an intervertebral implant in
a contracted configuration embodying features of the invention.
[0023] FIG. 2 is a perspective view of the implant shown in FIG. 1
in an expanded configuration.
[0024] FIG. 3 is an exploded perspective view of the implant shown
in FIG. 1.
[0025] FIG. 4A is a top view of the implant shown in FIG. 1.
[0026] FIG. 4B is a side cross-sectional view through line 4B-4B of
the implant shown in FIG. 4A.
[0027] FIG. 5A is a perspective view of a lower part of the implant
shown in FIG. 1 with upper portions and bottom face removed.
[0028] FIG. 5B is a bottom view of the lower portion shown in FIG.
5A.
[0029] FIG. 6A is a perspective view of the upper portion of the
implant shown in FIG. 1 with the lower portion removed.
[0030] FIG. 6B is an enlarged perspective view of the
staircase-like lower lock support shown in FIG. 3.
[0031] FIG. 7 is a partial side view of one of the locking
mechanisms of the implant shown in FIG. 2.
[0032] FIGS. 8A-9B are partial side views of the locking mechanism
in FIG. 7 shown in different expanded and locked
configurations.
[0033] FIGS. 10A and 10B of the locking mechanism illustrate the
expanded but unlocked configuration in FIG. 10A and the expanded
and locked configuration in FIG. 10B.
[0034] FIGS. 11A and 11B are perspective views of the lower lock
support and spring locking actuator illustrating the operation
thereof.
[0035] FIG. 11C is a perspective view of an alternative locking
mechanism and locking actuator embodying features of the
invention.
[0036] FIGS. 12A-12C are perspective views of alternative lower
lock support designs embodying features of the invention.
[0037] FIGS. 13A-13B are perspective and side views respectively of
an alternative implant embodying features of the invention which
has an articulating top end plate.
[0038] FIG. 14A is an exploded perspective view of yet another
alternative implant embodying features of the invention which has
the lower lock supports within the extendable pistons.
[0039] FIG. 14B is a top view of the implant shown in FIG. 14A.
[0040] FIG. 14C is a side cross-sectional view through line 14C-14C
of the implant shown in FIG. 14B.
[0041] FIG. 15 is a perspective view of an alternative implant
design having features of the invention wherein the locking
mechanism surrounds a central opening in the top end plate.
[0042] FIG. 16 is a perspective view of an alternative implant
design having features of the invention wherein the expanding
piston is centrally located and locking mechanisms are provided on
both sides of the expanding piston.
[0043] FIG. 17 is a simplified schematic illustration of an
alternative implant design having ratchet and pawl locking members
between the top and bottom plates of the implant.
[0044] FIG. 18 is a perspective view of an alternative implant
design with ratchet and pawl locking members between the top and
bottom plates of the implant.
[0045] FIG. 19 is a cross-sectional perspective view of an implant
design with ratchet and cantilevered spring members between the top
and bottom plates of the implant.
[0046] FIGS. 20A-20B, 21A-21B, 22-26, 27A-27B, and 28-29
schematically illustrate various means for locking an expanding
member of implants in extended configurations embodying features of
the invention.
[0047] FIG. 30 is a perspective view of yet another alternative
implant design having features of the invention wherein the locking
mechanism has straight upper and lower interfitting lock
supports.
[0048] FIG. 31A-31G illustrate an alternative implant locking
mechanism in which a wire-form surrounds a pair of upper support
members with grooves configured to receive the wire-form.
[0049] FIGS. 32A and 32B are perspective views of a further
alternative embodiment of the present invention including locking,
conical bone engaging anchors.
[0050] FIGS. 33A-C are perspective views showing alternative bone
engaging anchors.
[0051] FIGS. 34A and 34B are perspective cross-sectional views of
another alternative embodiment of the present invention including
locking, screw-threaded bone engaging anchors.
[0052] FIGS. 35A and 35B are perspective views of yet another
embodiment of the present invention including locking, telescoping
bone engaging surfaces.
[0053] FIGS. 36A and 36B are cross-sectional views of another
exemplary embodiment of the present invention shown in a collapsed
and an expanded configuration respectively.
[0054] FIG. 36C is a posterior perspective view of the embodiment
in FIG. 36B, shown in an expanded state.
[0055] FIGS. 37A and 37B are end views of a lift mechanism
according to a further exemplary embodiment of the present
invention, shown in a collapsed and an expanded configuration
respectively.
[0056] FIGS. 38A and 38B are end views of a cross section of
another embodiment of the present invention utilizing the lift
mechanism shown in FIGS. 37A and 37B, shown in a collapsed and an
expanded configuration, respectively.
[0057] FIGS. 39A and 39B are top views of the respective
embodiments shown in FIGS. 38A and 38B with the top plate
removed.
[0058] FIG. 40 is an anterior perspective view of the embodiment
shown in FIG. 38B.
[0059] FIG. 41 is a posterior perspective view of still another
exemplary embodiment of the present invention, shown in an expanded
configuration.
[0060] FIG. 42 is a perspective view of a lift mechanism of the
embodiment of FIG. 41.
[0061] FIGS. 43A and 43B are cross-sectional views of the
embodiment of FIG. 41 shown in a collapsed and an expanded
configuration, respectively.
[0062] FIG. 44 is an exploded perspective view of another
embodiment of the current invention.
[0063] FIG. 45A is a partial inferior perspective of another
embodiment of the present invention.
[0064] FIG. 45B is a partial top view of the embodiment shown in
FIG. 45A.
[0065] FIG. 46A is an exploded perspective view of another
embodiment of the current invention.
[0066] FIGS. 46B and 46C are superior perspective views of the
embodiment shown in FIG. 46A in the collapsed and expanded
configurations respectively.
[0067] FIG. 47 is an exploded perspective view of another
embodiment of the current invention.
[0068] FIG. 48 is an exploded perspective view of another
embodiment of the current invention
[0069] FIG. 49 is an exploded perspective view of another
embodiment of the current invention.
[0070] FIG. 50A is a side view of an alternative implant design in
a collapsed configuration having an articulating top plate.
[0071] FIG. 50B is a side view of the implant shown in FIG. 50A in
an expanded configuration.
[0072] FIG. 50C is a top view of the implant shown in FIG. 50B.
[0073] FIG. 50D is a side cross-sectional through line 50D of the
implant shown in FIG. 50C.
[0074] FIG. 51A is a side view of an alternative implant in a
collapsed configuration having an articulating top plate.
[0075] FIG. 51B is a side view of the implant shown in FIG. 51A in
an expanded configuration.
[0076] FIG. 52A is a side view of an alternative implant in a
collapsed configuration embodying features of the invention which
has two separated top plates.
[0077] FIG. 52B is a side view of the implant shown in FIG. 52A in
a slightly expanded configuration.
[0078] FIG. 52C is a side view of the implant shown in FIG. 52B in
a more expanded configuration.
[0079] FIG. 52D is a side view of the implant shown in FIG. 52C in
a fully expanded configuration.
[0080] FIG. 52E is a top view of the implant shown in FIG. 52D.
[0081] FIG. 52F is a side cross-sectional through line 52F of the
housing 111 of the implant shown in FIG. 52E.
[0082] FIG. 53 is a side view of an alternative implant design in a
fully expanded configuration having two separated top plates.
DETAILED DESCRIPTION
[0083] FIGS. 1-10B illustrate an example of an intervertebral
implant 10, a Selectively Expandable Cage (SEC), having features of
the invention. The implant 10 generally includes a housing 11, a
housing base 12, an interlocking top end plate 13, a bottom end
plate 14, an interior cavity 15 within the housing 11 and a pair of
cylinders 16. The top and bottom end plates are the bone engaging
members of the implant, providing surfaces for engaging vertebrae
above and below the implant when placed in the patient. Upper lock
supports 17 are attached to the underside of the top end plate 13
thus forming fixed lock members and have multi-stepped lower
support surfaces 18 much like an inverted staircase. Lower lock
supports 20, having multi-stepped upper support surfaces 21
surround cylinders 16 much like an upright staircase. The
multi-stepped support surfaces form the locking surfaces of the
lock supports. Pistons 22 are secured to the under surface of top
end plate 13. Seal members 23 are slidably disposed within the
cylinders 16 and are mounted on pistons 22. The upper surface 24 of
bottom end plate 14 is provided with locking actuator channels 25
which partially receive spring locking actuators 26. The base 12 of
the housing 11 has arcuate slots 27 which are configured to
slidably receive the depending elements 28 or locking actuator
transfer element of the lower lock supports 20 and partially
receive the spring locking actuators 26. Depending elements 28
engage the forward end 30 of spring locking actuators 26. The
spring locking actuators 26 are initially in a compressed
configuration so that upon the extension of the top end plate 13
and the attached upper lock supports 17, the lower lock supports 20
rotate about the cylinders 16 due to the force applied by the
biased spring locking actuator 26 thus forming moveable lock
members. This causes the lock support surfaces 21 of the lower lock
supports 20 to engage support surfaces 18 of the upper lock
supports so as to lock the top end plate 13 in an extended
configuration. The support surfaces 18 of the upper lock supports
17 and the support surfaces 21 of the lower lock supports 20 are
tiered with multiple steps so that the implant 10 can be locked at
several different expanded heights. The underside stepped support
surfaces 18 of the upper lock support 17 may be provided with
increasing riser height (alignment faces 46) in the upward
direction to provide smaller incremental expansion near the end of
the piston expansion. In addition or alternatively, the stepped
support surfaces 21 of the lower lock support 20 may be provided
with decreasing riser height in the upward direction for the same
reason. A variety of riser heights of the upper lock support 17 or
lower lock support 20 can be provided. The lowermost stepped
support surface 18 of the upper lock support 17 and the uppermost
stepped support surface 21 of the lower lock support 20 may be
provided with various lengths and widths to ensure better
support.
[0084] As can be seen in FIG. 2 there are two sets of upper lock
supports 17 attached to the top end plate 13 and there are two sets
of lower lock supports 20 in this embodiment, but a single set or
more than two sets of upper and lower lock supports can also be
used to lock the implant 10 in the expanded state. Also shown, for
example, in FIG. 2 are cylinders 16 and pistons 22, which provide
one example of extension means in embodiments of the present
invention. Other examples of extension means are described herein
below in connection with alternative embodiments of the
invention.
[0085] The implant 10 is configured to be implanted between
opposing vertebral bodies in the spine to facilitate bony fusion
between those vertebral bodies. The implant 10 is shown in its
collapsed or contracted configuration in FIG. 1 and in one example
of its expanded configuration in FIG. 2. In the collapsed state,
the implant 10 can be inserted easily into the intervertebral body
space through a minimal incision and with minimal tissue removal.
Once in that space, the implant 10 can be expanded against the two
opposing vertebral bodies to distract them and thereby restore
height to the intervertebral space. This provides stable opposition
of the implant 10 to both vertebral bodies and optimizes the bony
fusion process. The fusion process can also be enhanced by filling
the interior cavity 15 with autologous bone graft, a bone growth
enabling matrix, and/or bone growth stimulating substances prior to
and/or after insertion into the body.
[0086] Further details of individual parts of the implant 10 are
depicted in FIGS. 3, 4A and 4B. Pistons 22 are attached to the
underside of the top end plate 13 which are configured to support
seal members 23 which run inside of cylinders 16 located in the
housing 11. When the cylinders 16 are pressurized as will be
described in more detail below, the seals 23 running inside the
cylinders 16 and pistons 22 slidably disposed within the seals are
vertically displaced, translating the top end plate 13 vertically
above the housing 11. Lower lock supports 20 are located around the
outer wall of the cylinders 16. When the top end plate 13 is
vertically displaced, which in turn displaces the attached upper
lock supports 17, the lower lock supports are rotated by the biased
locking actuators 26 to a locking position. Arcuate locking
actuator channels 25 in the top surface of bottom plate 14 and the
arcuate slots 27 in the housing base 12 confines the locking
actuators 26 to the housing 11.
[0087] Additional details of the housing 11 are depicted in FIGS.
5A and 5B. The housing 11 comprises an outer wall 31 and cylinders
16 which are secured to housing base 12. The outer wall 31 supports
a leading nose 32 on the distal end and a delivery boss 33 on the
proximal end. The leading nose 32 has inwardly directed side
tapered faces 34 and top tapered face 35 and bottom tapered face
36. These tapered faces 34, 35 and 36 enable non-traumatic
insertion of the implant 10 past neural elements and between the
vertebral bodies. The delivery boss 33 contains a delivery tool
anchor 37 which allows secure attachment of the implant 10 to a
delivery tool (not shown), which is illustrated in co-pending
application Ser. No. 11/535,432, filed Sep. 26, 2006, and Ser. No.
11/692,800, filed Mar. 28, 2007 for insertion into a vertebral
space. The delivery boss 33 also contains pressure input ports 38
which are used to deliver a pressurized fluid to the interiors of
cylinders 16. The outer wall 31 of the housing 11 also provides
side openings 40 which provide space for bony in-growth into
central cavity 15 in the housing 11 and provide radiolucent
openings for the radiographic imaging of the process of bony
in-growth. The housing base 12 also contains pressure channels 41
which deliver pressurized fluid from the pressure input ports 38 to
the interior of cylinders 16. Although the housing base 12 of
implant 10 is depicted with independent pressure channel 41 for
each cylinder 16, other embodiments can contain one or more
branching pressure channels for delivering pressurized fluid to two
or more cylinders 16. As previously mentioned, the housing base 12
also has locking actuator slots 27 which hold and guide the locking
actuators 26. The locking actuator slots 27 contain a wider
portion, locking actuator opening 42, to enable insertion of the
locking actuator 26 into the channels defined by the locking
actuator slots 27 in housing base 12 and the locking actuator
channels 25 in the bottom end plate 14. The housing base 12 also
has optional alignment bosses 19 which align the bottom end plate
14 to the housing 11 via optional alignment holes 9.
[0088] FIGS. 6A and 6B illustrate further details of the top end
plate 13 and the lower lock support 20. The two sets of pistons 22
and upper lock supports 17 are joined by connecting members or
struts 44. The pistons 22 have seal bosses 45 on which the seals 23
are mounted. The upper lock supports 17 have tiered lower support
surfaces 18 and risers or alignment faces 46. The tiered or stepped
support surfaces 18 of the upper lock supports 17 engage the
stepped or tiered support surfaces 21 of the lower lock supports
20. The alignment faces 46 of the upper lock support are configured
to engage the alignment faces 47 of the lower lock supports 20. The
uppermost support surface of the lower lock support 20 has a lock
support stop 50 which engages with the lower most alignment faces
46 of the upper lock support to prevent the lower lock support 20
from over rotating as it engages the upper lock support 17. The
bottom of the lower lock support 20 also has the locking actuator
transfer element 28 which engages the forward end 30 of the spring
locking actuator 26 to transfer the actuation force from the
locking actuator 26 to the lower lock support 20.
[0089] FIGS. 7 through 10B show details of the selectively
expanding locking sequence of implant 10 with the housing 11
removed. The collapsed configuration is shown in FIG. 7 with the
support surfaces 18 of the upper lock support 17 resting on the
support surfaces 21 of the lower lock support 20. The locking
actuator 26 is a biasing element, such as a spring, that engages
the depending element or locking actuator transfer element 28 to
urge the alignment faces of the lock supports in a direction where
they contact. Thus, in one exemplary embodiment, the alignment
faces 47 of the lower lock supports 20 are forced against the
alignment faces 46 of the upper lock support 17. The lock support
stops 50 fit within the lower lock stop relief 52 (shown best in
FIG. 6A) on the top end plate 13. When the cylinders 16 are
pressurized, the pistons 22 raise the top end plate 13 and attached
upper lock supports 17 (straight arrow) moving the support surfaces
18 of the upper lock support 17 off of the support surfaces 21 and
moving the lower alignment faces 46 past the upper alignment faces
47. When the alignment faces 46 of the upper lock support 17 have
cleared the alignment faces 47 of the lower lock support 20, the
locking actuators 26 (in this embodiment a compressed coiled
spring) engaging the locking actuator transfer element 28 force the
lower lock supports 20 to rotate (curved arrow in FIGS. 8B and 9B).
The support surfaces 21 of the rotating lower lock supports 20 move
to the next lower level of the support surfaces 18 of the raised
upper lock supports 17 until the alignment faces 47 of the lower
lock supports 20 engage the next level of the alignment faces 46 of
the upper lock supports 17. The lower lock support 20 and upper
lock support 17 then lock the top end plate 13 at this expanded
level. This process repeats itself at each locking level (FIGS. 8A,
8B, 9A, 9B and 10A) until the top level (or somewhere between) is
reached as shown in FIG. 10B. At this top level, the locking
actuators 26 engage the locking actuator transfer elements 28 and
the lower lock supports 20 are rotated so the lowermost alignment
surface 46 of the upper lock support 17 engages lock support stop
50 of the uppermost support surface 21 of the lower lock support
20. At this highest locked level only the lowest support surfaces
18 of the upper lock supports 17 and the highest support surfaces
21 are engaged providing all of the locking support. As can be seen
from FIGS. 10A and 10B the lowest support surfaces 18 of the upper
lock supports 17 and the highest support surfaces 21 of the lower
lock supports 20 can be wider than the other support faces to
provide sufficient support material when only these two faces are
engaged.
[0090] FIGS. 11A and 11B illustrate the operation of locking
actuator 26. In this embodiment the spring locking actuator 26 is
compressed into an arc beneath the lower lock support 20. One end
of the spring locking actuator 26 is constrained by the housing 11
(not shown) and the other is engaged with the locking actuator
transfer element 28. When the lower alignment faces 46 of the upper
lock support 17 are raised above the upper alignment faces 47 of
the lower lock support 20 by the extension of piston 22, the
locking actuator 26 pushes against the locking actuator transfer
element 28 and rotates the lower lock support 20 in a clockwise
direction (arrow) as viewed from above. It should be noted that in
the embodiment of the current implant as described thus far, the
angular orientation of the tiered upper and lower support surfaces
18 and 21 can vary when there is more than one set of supports. As
shown in FIG. 3 the proximal lower support surfaces 21 are oriented
clockwise as viewed from above and the distal lower support
surfaces 21 are oriented counter-clockwise. This opposite
orientation provides enhanced locking support for rotational forces
applied to the implant.
[0091] An alternative locking actuator 26a is shown in FIG. 11C as
a torsion spring. This locking actuator 26a has constraining tab 53
secured to the lower lock support 20 and constraining tab 54
secured to the housing 11. Just as the compression spring shown in
FIGS. 11A and 11B applies a force to the lower lock support 20 to
rotate it, the torsion spring in FIG. 11C does the same. An
extension spring would work equally as well as a locking actuator
26a. Spring actuators can be made of an appropriate biocompatible
material such as stainless steel, NITINOL, titanium or a suitable
polymer. Locking actuators are not limited to springs. A wide
variety of mechanisms can be used to actuate the lower lock
supports 20, including but not limited to, a linear drive, an
externally actuated tensile member, a worm gear, an inflated member
such as a balloon or bellows, a magnet, a rotational drive such as
a micro motor, a super elastic shape memory element, and the
like.
[0092] FIG. 12A through 12C show variations of the lower lock
support 20 described above. In FIG. 12A a tri-set lock support 20a
is shown whereby there are three sets of upper support surfaces
21a, upper alignment surfaces 47a and lock support stops 50a rather
than the two sets described above. This tri-set lower lock support
20a has two advantages over the two sets design, 1) there are three
support columns rather than two locking the implant 10 in an
expanded state thereby creating a more stable lock and 2) the
tri-set lower lock support 20a has to move or rotate much less for
each locking level. This last advantage is significant when the
locking actuator is a spring such as spring locking actuator 26 as
this places less strain on the spring to achieve the required
locking force at each step. Each lower lock support column will
have a corresponding upper lock support column (not shown). The
upper support surfaces 21 and lower support surfaces 18 are not
limited to two or three sets of surfaces. Any number of sets of
support surfaces including a single set may be employed.
[0093] FIG. 12B shows an inter-digitating lower lock support 20b.
Each of the inter-digitating upper support surfaces 21b on the
inter-digitating lock support 20b is paired with an
inter-digitating stop 50b which when paired with matching
inter-digitating support surfaces and stops of an upper lock
support (not shown) prevents the inter-digitating support surfaces
21b from moving relative to the inter-digitating support surfaces
of an upper lock support to unlock the implant without the
inter-digitating lower support faces first lifting above the
inter-digitating stop 50b. This design provides an enhanced locking
feature. Upper alignment surfaces 47b are again provided.
[0094] Generally the lower support surfaces 18 and the upper
support surfaces 21 are horizontal to maximize vertical support in
the locked implant. However, the locking support 20c shown in FIG.
12C provides an enhanced locking feature by providing inclined
support surfaces 21c which have a slope relative to the horizontal
which requires matching inclined lower support surfaces on the
upper lock supports (not shown) to be lifted above the inclined
upper support surfaces 21c before the upper lock support can be
rotated to unlock the implant.
[0095] FIGS. 12A and 12C show various lengths of locking actuator
transfer elements or depending elements 28. The locking actuator
transfer element 28 can vary in length depending on how much
engagement is desired between the locking actuator transfer element
28 and the locking actuator slots 27. The locking actuator transfer
element 28 includes one or more transfer element tabs 29a and 29c
which vertically constrain the lower lock support 20 to the locking
actuator slots 27 in the housing 11. The wider locking actuator
opening 42 described above (see FIG. 5B) enables insertion of the
locking actuator transfer element 28 with transfer element tabs 29a
and 29c into the locking actuator slots 27 in housing base 12 at
the rotational position where the locking actuator transfer element
28 is aligned with the locking actuator opening 42. In other
rotational positions the transfer element tabs are constrained by
lateral extensions on the sides of the narrower locking actuator
slots 27. In this manner the locking actuator transfer element 28
provides both the function of transferring force from the locking
actuator 26 to the lower lock support 20 as well as constraining
the lower lock support 20 to the housing 11. This later function
prevents the frictional forces between the lower alignment faces 46
and the upper alignment faces 47 created by the biased spring
locking actuator 26 from lifting the lower lock support 20 along
with the upper lock support 17 when the upper lock support 17 is
lifted by the piston 22.
[0096] As an alternative to the locking actuator transfer element
28, the embodiment shown in FIG. 12B depicts a locking actuator
guide channel 80. This locking actuator guide channel 80 engages a
tensile member (not shown) which transfers actuation force from the
locking actuator 26 to the lower lock support 20. Tensile members
can be any of a number of known elements such as sutures made of
polymers or natural materials, metal cable, plastic or metal rod
and the like.
[0097] FIGS. 13A and 13B illustrate an alternative design of an
implant 110 embodying features of the invention. The implant 110
has independent actuation of the distal piston 122a and proximal
piston 122b. The two pistons 122a and 122b are interconnected by an
articulating top end plate 113 which allows independent lift and
locking of each side of the implant 110. This independent lift and
locking of both ends of the implant 110 enables the implant to
conform to intervertebralend plates that have uneven lateral
heights between them. Further, this independent lift and locking
allows the implant 110 to be used to create varying lateral heights
between vertebralend plates which can be useful to compensate for a
scoliosis in the spine.
[0098] Implant 110 has a housing 111 which has an alternative
delivery tool anchor 160 located in it as well as alternative
pressure input ports 137. A variety of anchor designs or pressure
ports can be used with any of the embodiments of the current device
without departing from the scope of this invention. Lock and unlock
access ports 138 are also located on this housing 111. These ports
are used to guide lock and unlock mechanisms (not shown) which can
be manipulated externally to the implant 110 to actuate the lower
lock support 120 to not only move it under the upper lock support
117 to hold the piston 122b and articulating end plate 113 in an
expanded position, but also to move the lower lock support 120 away
from the upper lock support 117 to allow the piston 122b and
articulating end plate 113 to collapse back into the housing 111.
This later action may be desirable to remove the implant 110 from
or reposition the implant within the intervertebral space. A
variety of lock/unlock mechanisms can be used with the current
invention such as but not limited by, a tensile member including
suture thread and metallic cable, a compressive member such as a
metallic or polymer rod, pressurized fluid, a rotating drive, a
super elastic shape memory element, and the like.
[0099] FIGS. 14A-14C depict yet another alternative implant 210
that embodies features of the invention. Implant 210 has an
interfacing top plate 213 which connects to separate and freely
rotating pistons 222 via the piston capture plate 270 on the
interfacing top plate 213 and the piston heads 271 on the rotating
pistons 222ab. The rotating pistons 222ab also interiorly contain
upper lock supports 217 with support faces 218 and alignment faces
246. Seals 223 are mounted on the rotating pistons 222ab and the
seals 223 and rotating pistons 222ab fit into internal cylinders
216 that are located on the housing 211. The internal cylinders 216
have lower lock supports 220 with support surfaces 221 and
alignment faces 247 as well as lower retaining features 273. The
housing 211 also contains one or more pressure input ports 238.
[0100] In use, the implant 210 is inserted into the intervertebral
body space in a collapsed state and fluid pressure is delivered
through the pressure input port(s) 238 to the internal cylinder(s)
216 to raise the seal(s) 223 and rotating piston(s) 222ab out of
the internal cylinder(s) thereby raising the interfacing top plate
213 and expanding the implant 210. Once the rotating pistons 222ab
have been raised such that the lower alignment faces 246 of the
upper lock supports 217 have cleared the upper alignment surfaces
247 of lower lock supports 220, an actuator (not shown) rotates the
rotating pistons 222ab such that the lower support surfaces 218 of
the upper lock supports 217 are moved above the upper support
surfaces 221 of the lower lock supports 220, to thereby lock the
implant 210 in the expanded configuration. The actuator can be one
or more tensile members such as suture threads or cables that
extend from the user into the implant 210 through the lock and
unlock access ports 238 on the interfacing top plate 213 to the
piston head 271. Applying tension to one or more tensile members
when the piston is in an extended configuration will rotate the
piston heads 271 such that the support surfaces 218 of upper lock
supports 217 are moved above the support surfaces 221 of the lower
lock supports 220 thereby locking the implant 210. Alternatively or
in addition to applying tension to lock the implant 210 in an
expanded configuration, applying tension to one or more tensile
members will rotate the piston heads 271 such that the lower
support surfaces 218 are moved away from the upper support surfaces
221 thereby unlocking the implant 210 and allowing the rotating
pistons 222ab to seat back into the internal cylinders 216 such
that the implant 210 is once again in a collapsed
configuration.
[0101] FIG. 15 illustrates an alternative implant design 310
embodying features of the invention which has a housing 311, top
end plate 313 and pistons 322 similar to the prior embodiments.
This implant 310 has upper lock supports 317 and lower lock
supports 320 within a central portion of the implant. The upper
lock supports 317 are secured to the top end plate 313 and the
lower lock supports 320 are secured to the base 314 with depending
elements (not shown) as was described above and are moved as in the
prior embodiments.
[0102] FIG. 16 illustrates an alternative implant design 410
embodying features of the invention which has a housing 411, top
end plate 413 and a centrally located piston 422 similar to the
prior embodiments. This implant 410 has upper lock supports 417 and
lower lock supports 420 distal and proximal to the centrally
located cylinder 416 and piston 422. The upper lock supports 417
are secured to the top end plate 413 and the lower lock supports
420 are secured to the base 412 and are moved as in the prior
embodiments via depending elements (not shown) as was described
above.
[0103] FIG. 17 shows another alternative implant 510 which has a
pair of pistons 522 and which has a locking support system which
includes ratchets 521 on the base 512 and pawls 517 pivotally
mounted to and depending from the top end plate 513. Expansion of
the pistons 522 causes the free ends 518 of pawls 517 to engage
recesses 520 in the ratchets 521 so as to lock the top end plate
513 in an extended configuration.
[0104] FIG. 18 illustrates another alternative implant design 610
which is similar to that shown in FIG. 17. In this embodiment the
free end of the pawl 617 has a plurality of teeth 618 to provide
greater effective contact between the pawl 617 and the ratchet 621
for locking of the implant 610.
[0105] FIG. 19 is a cross section embodiment, showing implant 710
embodying features of the invention. In this embodiment the pistons
722 are surrounded by upper lock support 717 which has at least one
cantilever extension ending at the support surface 718. The support
surfaces 718 are captured by the recessed support surfaces 721
which are located on the inner wall of the housing 711. Once the
pistons 722 are expanded in an upward direction, the support
surfaces 718 of the upper lock support 717 engages the recessed
support surfaces 721 locking the implant 710 in place. The upper
lock support 717 can be rotated relative to the piston 722 and
housing 711 to disengage the support surfaces 718 from the support
surfaces 721 to unlock the implant 710 and lower the pistons 722 as
needed. Alternatively the implant 710 can be unlocked by rotating
the upper lock support constraints 775 relative to the upper lock
support 717 to press on the cantilever extensions and disengage the
support surfaces 718 from the support surfaces 721.
[0106] FIGS. 20A-31 illustrate a variety of suitable means for
locking extendable members such as pistons in extended
configurations. FIGS. 20A, 20B, 21A, 21B, and 22-31 show variations
of lower lock supports and upper lock supports. In each of these
variations there are support surfaces on the lower lock supports
which engage support surfaces on the upper lock supports.
[0107] In FIGS. 20A and 20B support surfaces 818 comprise grooves
set into the upper lock support 817. The lower lock support 820 is
a U-shaped tong which is configured to advance (as indicated by the
arrow in FIG. 20A) towards the upper lock support 817 and to engage
one of the grooves with its upper support surface 821 for locking
an implant not shown in these drawings. Lower lock support 820 is
withdrawn (as indicated by the arrow in FIG. 20B) from the groove
to disengage the lower lock support and unlock the implant.
[0108] In the variation shown in FIG. 21A, the lower lock support
920 is a plate with an upper lock clearance opening 970 that is
shaped to allow passage of the cylindrical flat-sided upper lock
support 917 through the lower lock support 920 (arrow). As shown in
FIG. 21B, once the lower lock support 920 is positioned at the
desired location it can be rotated approximately 90.degree. (arrow)
to engage the support surfaces of the lower lock support 920 with
the support surfaces 918 of the upper lock support 917. The shape
of the upper lock support 917 and mating upper lock clearance
opening 970 on the lower lock support 920 are not restricted to the
profile shown in FIGS. 21A and 21B nor is the locking actuation
restricted to 90.degree. rotation of one of the elements but can
vary to any number of shapes that allow passage in one
configuration but constraint when one of the elements is moved to
another configuration.
[0109] In FIG. 22, the upper lock support 1017 is a cylinder with
notches cut to create support surfaces 1018. The lower lock support
1020 is a pivoting pin 1070 with a pawl 1071 for the lower support
surface 1021. In the configuration shown, the support surface is
biased as indicated by the arrow 1072 to allow the upper lock
support 1017 to rise with an expandable member of an implant and to
prevent the upper lock support from dropping. This allows the
device to lock at each level when the subsequent support surface
1018 of the upper lock support 1017 engages the support surface
1021 of the lower lock support 1020. In this variation having
features of the present invention, the upper lock support 1017 can
also be lowered by moving the pivoting pin 1070 of the lower lock
support 1020 away from the upper lock support 1017 to disengage the
support surface 1021 from the support surface 1018.
[0110] FIG. 23 shows yet another embodiment having features of the
invention where the lower lock support 1120 is a pin configured to
engage (arrow) support surfaces 1118 located in the upper lock
support 1117. The lower lock support 1120 does not have to engage
the full thickness of the upper lock support 1117 as shown in this
figure, nor does the support surface 1118 have to extend through
the entire thickness of the upper lock support 1117 but rather can
engage any portion of the upper lock support 1117 that is
sufficient to lock an implant in position. This embodiment also
allows a variety of shapes of pins 1120 and matching support
surfaces 1118.
[0111] In FIG. 24 the lower lock support 1220 is a grip with two
pivoting jaws 1270, the ends of which have support surfaces 1221.
The upper lock support 1217 has a series of notches which have the
support surfaces 1218. A lock actuator such as a compressive spring
(not shown) can apply force (as shown by the arrows 1272) to the
grip base extensions 1273 to lock the device. This variation having
features of the invention allows the upper lock support 1217 to
move upwards but prevents downward motion thereof. Downward motion
of the upper lock support 1217 can be allowed by reversing the
force on grip base extensions 1273.
[0112] Not all locking systems embodying features of the invention
require the engagement of support surfaces of the upper lock
supports directly on top of the support surfaces of the lower lock
supports. A frictional support can be created to lock the device as
shown in FIGS. 25 through 32.
[0113] In FIG. 25 the upper lock support 1317 has one or more flat
surfaces as the support surfaces 1318. The lower lock support 1320
has one or more pivoting pawls that have a support surface 1321
that engage the support surface 1318 and supports a load
(arrow).
[0114] In FIG. 26 the upper lock support 1417 has an exterior
support face 1418 which is gripped by the support face 1421 on the
inner diameter of the wrapped lower lock support 1420. This lower
lock support 1420 can be a torsion spring that in its free state
grips the upper lock support 1417 and releases the upper lock
support when a force (arrows) is applied to one or more of its ends
1470 as shown to increase the spring's inner diameter. The reverse
is possible where in its free state the lower lock support 1420
allows movement of the upper lock support 1417 inside the inner
diameter. When a tensile force is applied to the ends 1470 to
reduce the inner diameter, the lower lock support grips the support
surface 1418 of the upper lock support 1417 to lock the
implant.
[0115] FIGS. 27A and 27B show another variation which can be
described as a canted washer type device. The lower lock support
1520 is a plate with an upper lock clearance opening 1570 which
allows relative movement of the upper lock support 1517 as shown in
FIG. 27A. When the lower lock support 1520 is canted as shown in
FIG. 28B, the edge of the upper lock clearance opening 1570
comprises a lower support surface 1521 which engages the upper
support surface 1518 which is the outer surface of the upper lock
support 1517 locking it relative to the lower lock support
1520.
[0116] Yet another variation of the gripping lock of the current
invention is shown in FIG. 28. In this variation the lower lock
support 1620 comprises one or more jaws which have support surfaces
1621 that are configured to be forced against the support surface
1618 of the upper lock support 1617 to produce friction to lock the
device in place.
[0117] FIG. 29 illustrates a lower lock support 1720 which
comprises a pivot and pawl as has been detailed above. The end of
the pawl comprises a lower support surface 1721 which engages an
upper support surface 1718 on the upper lock support 1717. In this
embodiment the upper lock support 1717 is rotated counter clockwise
by an expanding element (not shown). This rotation in turn raises
the piston 1722 which expands the implant. In this manner the upper
lock support 1717 is integrated into the lifting mechanism to
engage the lower lock support 1720 and lock the implant as it
expands.
[0118] FIG. 30 illustrates yet another alternative implant 1810,
similar to that shown in FIG. 1 except that the upper locking
member 1817 and lower locking member 1818 have a linear shape
rather than the arcuate shape of the prior embodiments. The implant
1810 generally has a housing 1811, a top plate 1813, a bottom plate
1814, pistons 1822 and cylinders 1816. The upper locking member
1817 has support surfaces 1818 and the lower locking member 1820
has support surfaces 1821. The implant 1810 has a locking actuator
(not shown).
[0119] FIGS. 31A-31G illustrate another implant 1910 embodying
features of the invention which have upper locking members 1917
with grooves 1970 having support surfaces 1918 and lower locking
member 1920 with locking surfaces 1921. The lower locking member
1920 is a wire-form which encircles the exterior of both upper
locking members 1917 and is configured to seat within the grooves
1970. Expansion of the lower locking member 1920 (arrows in FIG.
31B) by the locking actuator (not shown) causes the lower locking
member 1920 to be pulled out of the groove 1970 and allows the
upper locking member 1917 to rise with the expansion of the
implant. Release of this expansion of the lower locking member 1920
(arrows in FIG. 31A) allows the lower locking member 1920 to seat
back into the groove 1970 locking the implant 1910.
[0120] FIG. 31G illustrates a detail of an alternative implant
1910a embodying features of the invention which have upper locking
members 1917a with grooves 1970a having support surfaces 1918a and
lower locking member 1920a with locking surfaces 1921a. The lower
locking member 1920a is a wire-form which encircles the exterior of
both upper locking members 1917a and is configured to seat within
the grooves 1970a. The support surface 1918a locks on the support
surface 1921a when there is a compressive or downward force (hollow
arrow) on the upper locking member 1917a locking the implant 1910a.
Upward force or extension (solid arrow) of the upper locking member
1917a causes the lower locking member 1920a to ride on the
disengaging surface 1919a and out of the groove 1970a allowing the
upper locking member 1917a to rise with the expansion of the
implant 1910a.
[0121] In a further aspect of the present invention, a
piston/cylinder and locking arrangement as described above may be
used to deploy extendable bone anchors. For example, implant 10A
with conical bone engaging anchors 60 as shown in FIGS. 32A and 32B
may be constructed with pistons 22 and cylinders 16 as described
above in connection with implant 10 and shown, for example, in
FIGS. 2, 3 and 4B. Implant 10A has a housing 11 as previously
described and may include other previously described features such
as interior cavity 15 for bone growth stimulating substances.
However, in this embodiment, instead of upper interlocking end
plate 13, the two pistons 22 individually terminate with conical
bone engaging anchors 60. The bone engaging anchors, including
sharp leading tip 62, form surface for engaging the vertebral
body.
[0122] As shown in FIG. 32A, bone engaging anchors 60 are in a
contracted configuration, within housing 11, to facilitate
insertion of implant 10A. Using hydraulic actuation as previously
described, bone engaging anchors 60 are moved to an extended
configuration as shown in FIG. 32B, wherein at least leading tip 62
extends beyond housing 11 to engage and anchor in the bone. In
order to ensure that the bone engaging anchors remain firmly
engaged in the bone, locking mechanisms including multi-stepped
upper and lower lock supports 17, 20 as previously described in
connection with implant 10 and shown, e.g. in FIGS. 6A-12C, are
provided to support each anchor 60 in the extended configuration.
With this arrangement, the extended and locked anchor 60 helps to
retain the implant in place.
[0123] A variety of alternatives are possible for the bone engaging
anchor according to the invention as illustrated in FIGS. 33A-C.
For example, implant 10B in FIG. 33A includes bone engaging anchors
formed as spike 60A and blade 60B. Blade 60B can be particularly
effective in preventing motion along the insertion path after
deployment. In this case, the length of the blade 60B is aligned in
the direction shown by arrow A. This is substantially orthogonal to
the direction of implantation (arrow B) and would resist movement
in that direction. Implant 10F, shown in FIG. 33B includes further
possible variations. In this embodiment, the bone engaging anchors
are formed as barbed spikes 60C. Barbs 61 along the shaft of the
spikes resist forces that tend to move the tissue away from the
implant along the axis of the anchor (much as the screw threaded
anchor described below would also resist this force). Also included
in implant 10F is a lateral bone engaging anchor 63 for anchoring
in laterally oriented tissue. In the illustrated embodiment,
lateral anchor 63 includes a plain spike 60A. Lateral anchor 63 is
formed in the same manner and with the same components, i.e.
piston, cylinder, locking mechanism, etc. as elsewhere described in
this application, except that the components are oriented laterally
as shown. To provide support for the bone anchor components in this
lateral embodiment, housing 11 includes a central member 11A that
divides interior cavity 15 into two portions. In the configurations
of implants 10B and 10F, the top of piston 22 can also become a
bone engaging surface when the anchor member is fully received
within the bone. FIG. 33C shows a further alternative implant 10G,
including anchors 65 extending obliquely from housing 11, rather
than orthogonally. This oblique arrangement is helpful in resisting
side to side rotational forces (for example when the patient/spine
bends towards the side) and expansion forces. Once again, obliquely
extending anchors 65 are essentially identical to other bone
engaging anchors described herein except for the oblique
orientation. Here, holes 68 are provided in top end plate 66 for
the spikes to pass through. In general, bone engaging anchors
according to embodiments of the invention should have a relatively
small termination (e.g. tip 62) relative to the size of the piston
diameter so that the force on the piston created by the hydraulic
fluid is proportionally a much greater force at the small anchor
termination to enhance its ability to extend into hard bony
tissues. It will also be appreciated by persons skilled in the art
that the various features of the bone engaging elements, e.g.
spike, blade, barbs, etc., described herein may be combined in any
desired combination, in addition to the exemplary combinations
shown in the figures of the present application.
[0124] In another alternative embodiment, illustrated in FIGS. 34A
and 34B, implant 10C includes screw-threaded members 64 as bone
engaging anchors. Implant 10C also illustrates a further
alternative wherein the bone engaging surfaces, such as the
anchors, extend from opposite sides of the implant. In this
exemplary embodiment, interlocking end plate 13 is replaced with an
integrated top end plate 66. Holes 68 are provided for threaded
member 64 to pass through. Persons of ordinary skill in the art
will appreciate that holes 68 will be located as needed; in the
illustrated embodiment one is in top end plate 66 and the other in
bottom end plate 14.
[0125] Threaded members 64, as bone engaging anchors extend
outwardly from pistons 22. In order to rotate the threaded anchors
into the bone when the pistons are extended, the inner wall of
housing 11 is provided with a screw-threaded surface 70 that mates
with corresponding threads 71 cooperating with pistons 22. As
previously described, seals 23 act between the pistons 22 and
cylinders 16 to prevent leakage of hydraulic fluid. When fluid is
pressurized within the cylinders as described for prior
embodiments, the piston is extended, but also driven in a circular
motion by the engagement between threaded surfaces 70 and 71. The
screw-threaded member 64 is thus driven into adjacent bone as it is
extended to anchor the implant.
[0126] Once again, locking mechanisms as previously described and
shown, for example, in FIGS. 6A-12C, may be employed to prevent the
bone engaging anchors from becoming unengaged from the bone. In the
cross-sectional views of FIGS. 34A and 34B, upper and lower lock
supports 17, 20 are visible around the outside of the piston and
cylinders. Alternatively, depending on the depth and pitch of the
threaded portions, use of a separate locking mechanism may not be
required. As persons of ordinary skill will appreciate, the
configuration of the threads alone may be sufficient to prevent the
anchors from backing out.
[0127] FIGS. 35A and 35B illustrate a further aspect of the present
invention wherein locking mechanisms as described are utilized to
secure telescoping bone engaging surfaces in place. As used herein,
telescoping refers to nested, extendable members including at least
one intermediate member between a base and bone engaging
member.
[0128] Referring first to FIG. 35A, implant 10D has substantially
planar bone engaging members 72. Bone engaging members 72 are thus
similar to the bone engaging members of implant 10, but instead
individually actuated without interlocking end plate 13. The
piston/cylinder arrangement is also similar to that previously
described except that here upper piston 74 is received in
intermediate piston 80. Intermediate piston is in turn received in
cylinder 16 as was previously described for piston 22. Upper piston
74 is sealed against intermediate cylinder 78 of intermediate
piston by upper piston seals 76 (see FIG. 35B).
[0129] The telescoping bone engaging members 72 are secured by
locking mechanisms in a similar manner to the earlier described
embodiments, with the addition of an upper lock support 82 for the
upper piston. Intermediate piston 80 is supported by upper lock
support 17 and lower lock support 20 as previously described. Upper
lock support 82 includes upper and lower lock supports 84, 86.
Thus, upper piston 74 is secured to upper lock support 84 of the
upper lock set. Lower lock support 86 of the upper lock set is
mounted on top of upper lock support 20 of the lower lock set. One
difference from the earlier described embodiments is that separate
spring actuators 26 are not required for the upper lock set as they
may be rotated along with the lower lock set by actuators 26.
[0130] Implant 10E, as shown in FIG. 35B includes a further
variation in which the planar portion of upper bone engaging
surface 88 is effectively annular with a conical anchor 90 at the
center. Advantages of embodiments of the present invention
including bone engaging anchors include the ability of the anchors
to be extended lateral from the long axis of the implant (i.e., the
insertion axis) with a relatively high force using the relatively
small connection to the implant of the hydraulic line. This is an
advantage over other methods that require larger access or larger
connections to the implant for lager tools or non-hydraulic
extension forces to extend the anchors into the hard, bony
tissue.
[0131] Although the previously described embodiments of the
invention included cylinders 16 and pistons 22 expanded with a
pressurized fluid as the mechanism used to lift the top end plate
away from the bottom end plate, embodiments of the present
invention are not limited to only such lift mechanisms. In FIGS.
36A-C an alternative embodiment of the present invention comprising
implant 10F is shown wherein a pair of bellows 92 replaces the
piston and cylinder pairs previously described. One end of bellows
92 is attached to housing 11 and the other end to top end plate 13.
A pressurized fluid added via pressure input ports 38 is directed
through bellows orifice 94 into the inside of bellows 92 causing
the bellows to expand. The expanding bellows forces top end plate
13 away from housing 11 and lower lock supports 20 are rotated to
lock the device in the expanded configuration as was previously
described. Bellows 92 can be made of any biocompatible material
such as the 316 series of stainless steels, titanium or a titanium
alloy, a cobalt chromium alloy, or an implantable polymeric
material. The bellows can be of an accordion-like folding
configuration as shown in FIG. 36A-C or any other regular or
irregular configuration which can fit inside of the housing and
lock supports in the collapsed configuration and expand
sufficiently when pressurized to lift top end plate 13 the desired
amount away from housing 11. Lower lock supports 20 and upper lock
supports 17 provide a confining geometry for bellows 92, which
allows use of an irregular bellows configuration. With a bellows
arrangement as shown in FIGS. 36A and 36B, the amount of lift is
not limited as is the case in a cylinder and piston to the amount
that the collapsed cylinder and piston overlap.
[0132] Other exemplary embodiments do not rely on the use of a
pressurized fluid for expansion. For example, FIGS. 37A and 37B
show an alternative rotating cam lift mechanism 93. Cam lift
mechanism 93 includes cam 96 with a substantially curved cam
surface 95 and a substantially flat top surface 97, rotating shaft
98, and shaft supports 99. Cam 96 is attached to rotating shaft 98,
and shaft 98 is supported by and rotates within shaft supports 99.
In an implant 10G (FIG. 40) using this mechanism, the shaft
supports 99 are anchored to the inside of housing 11 and rotation
of shaft 98 (depicted by curved arrows) rotates the curved cam
surface 95 against the bottom of top end plate 13 and moves top end
plate 13 away from housing 11 as shown in FIGS. 38A-38B, 39A-39B
and 40. The shape of cam 96 determines both the amount of lift that
is possible and the relative amount of lift to the amount of
rotation of the cam. The cam is not limited by 90 degrees of
rotation depicted in the figures. Any shape of a cam that is
rotated by any amount from as little as 10 degrees to as much as
355 degrees is possible without departing from the scope of the
present invention. Shaft rotation can be accomplished by several
means as will be discussed in more detail below. Use of cam lift
mechanism 93 as the lifting mechanism along with lower and upper
locking supports 20 and 17 for implant 10G allows the lift
mechanism to support only the initial lifting loads and not have to
support the repetitive long-term supporting loads on implant 10G
which are borne by the locking supports. Cam 96 does not require a
substantially flat top surface 97 as shown in the exemplary
embodiment to support top end plate 13, but such a surface provides
a rotational endpoint for the surgeon rotating shaft 98.
[0133] Another alternative embodiment is implant 10H shown in FIGS.
41, 43A and 43B. Implant 10H uses a rotating screw lift mechanism
193 as shown in FIG. 42. This mechanism includes shaft 98, shaft
supports 99, worm gears 170 attached to shaft 98 and a shaft input
end 178 at one end of shaft 98. The mechanism also includes lift
screws 172, which have lower lift threads 174 and transfer gear 176
and supporting boss 186. Applying a torque via shaft input end 178
turns shaft 98, which turns the attached worm gears 170. Worm gears
170 turn transfer gear 176 on lift screw 172. Lift screw 172 is
contained within housing 11 by way of its supporting boss 186,
which is seated in housing bearing 188. Rotation of lift screw 172
transfers force from lower lift threads 174 to upper lift threads
182 on upper lift nut 180. Upper lift nut 180 is attached to top
end plate 13 so that rotation of shaft input end 178 lifts upper
end plate 13 away from housing 11. The relative pitch of worm gears
170 and matching transfer gears 176 and the lower lift threads 174
and matching upper lift threads 182 can be varied to achieve the
desired amount of lift relative to the amount of rotation and
torque. The torque can be applied by any means well known by those
skilled in the art including but not limited to electric motor,
pneumatic or hydraulic turbine, or manual rotation of an actuator.
Shaft input end 178 is shown as a hexagonal post, but any
alternative input end can be used without departing from the scope
of the present invention, such as, but not limited to, a square or
star-shaped post, a square, star or hexagonal-shaped socket, or a
keyed shaft.
[0134] As shown in FIG. 44, an alternative embodiment of the
implant 10I includes a linking element 202 that connects the lower
lock supports 20A and 20B. The linking element 202 coordinates the
action of the lower lock supports 20A and 20B. When the locking
actuator 26 actuates the leading lower lock support 20A, the
linking element 202 in turn actuates the following lower lock
support 20B. In this embodiment the implant 10I may require only a
single locking actuator 26, however plural locking actuators as
described above (see, for example, FIG. 3) may be employed for
greater actuation force as needed. In addition to actuating the
following lower lock support 20B, the linking element 202 prevents
the leading lower lock support 20A from actuating until the
alignment faces 46 of both the leading upper lock supports 17A and
the following upper lock supports 17B each clear the alignment
faces 47 of both the leading lower lock support 20A and the
following lock support 20B. In this manner the linking element 202
ensures the coordinated actuation of the lower lock supports 20A
and 20B to ensure that the implant 10I will always lock at the same
height on both sides. This can be advantageous for certain implants
placed in the spine where an even expansion of the implant is
desired.
[0135] Linking plural lower lock supports, such as supports 20A and
20B, with a linking element 202 for even expansion in the manner
described may be advantageous over an implant with a similarly
sized single lock support 20, and single cylinder 16 and piston 22
due to the increase in the number of support elements, the broader
support base, and the increase in expansion force due to the
increased number of cylinder and piston pairs. Increasing the size
of a single lock support would still have disadvantages of a larger
width that would limit the ability for implantation in minimally
invasive surgery. Embodiments of the invention are not limited to
just the pair of lower locking supports 20A and 20 B as shown in,
for example, FIG. 33. Rather, any number of sets of cylinders 16,
pistons 22, upper lock supports 17, and lower lock supports 20,
with a locking actuator 26 and the appropriate number of linking
elements 202 are possible.
[0136] For the embodiment illustrated in FIG. 44, linking element
202 is configured to fit inside attachment grooves 204 on the lower
lock support 20A, B. Alternatively, linking element 202 may be
configured to rest on the outside diameter of the lower lock
support 20A, B. The linking element 202 can also be configured to
run underneath the lower lock supports 20A, B as shown in FIGS.
45A-D. For implant 10I in FIG. 44 both of the lower lock supports
20A and 20B rotate in the same direction when actuated. Elements of
an alternative implant shown in FIGS. 45A-B include lower lock
supports 20 that actuate with rotation in opposite directions. The
linking element 202 is guided between the lower lock supports 20
through a link channel 210 in housing 11 (FIG. 45B). The linking
element 202 is constrained in the link channel 210 by a channel
cover 208. The linking element 202 is connected to the lower lock
supports 20 by means of link pins 206.
[0137] The linking element can be made from any of a variety of
implantable materials including: a titanium wire, a titanium cable,
a stainless steel wire or cable, a nitinol wire, a braided or
mono-filament suture from any manner of suture material such as
silk, polyester, polypropolyene, ePTFE, or UHWPE. An implantable
material that has a tensile strength sufficient to transfer the
actuation force from the leading lower lock support 20A to the
following lower lock support 20B as well as flexibility sufficient
to follow the link channel 210 and/or rotate around the lock
supports 20 may be used. Linking element 202 can be attached to the
lower lock supports 20 in a number of ways known to those practiced
in the art, the selection of which depends on factors such as the
linking element material and the lower lock support material.
Suitable techniques include laser welding, resistance welding,
adhesive bonding, crimping, attaching with clamps, pins, or screws,
or being threaded through an opening and securing with a knot.
[0138] Turning now to FIGS. 46A, B and C an implant 10J with an
additional feature, an unlocking tether 212 is shown. Unlocking
tether 212 is attached to the following lower lock support 20B in
attachment groove 204. Unlocking tether 212 is attached in the
opposite direction as the linking element 202 and can be attached
in any of the ways described above for attaching the link element
202. The proximal end 214 of the unlocking tether 212 exits the
housing 11 of the implant 10J through the unlock port 216. The
proximal end 214 can be actuated by an external force or mechanism
(not shown). Actuation of the proximal end 214 of the unlocking
tether 212 to translate it away from the implant 10J causes
rotation of the following lower lock support 20B, which will
tension and translate the linking element 202 which will rotate the
leading lower lock support 20A. In this manner the unlocking tether
212 can be used to unlock the implant 10J so that it can collapse
to a lower or to its original height. In FIG. 46B the implant 10J
is collapsed and the unlocking tether 212 is extended a maximum
distance out of the unlock port 216. FIG. 46C shows the same
implant 10J with the top plate 13 fully expanded above the housing
11 and locked. The unlocking tether 212 has shortened as it was
drawn into the implant 10J as the lower lock supports 20 rotated
into locking position. Tensioning or pulling on the unlocking
tether 212 will unlock the lower lock supports 20 and allow the top
plate 13 to collapse back into the housing 11. The ability to
unlock and collapse the implant 10J can be highly advantageous to a
physician placing the device if there is a need to reposition or
replace the device after it has been expanded in-vivo.
[0139] Turning now to FIG. 47, another embodiment of an implant 10K
is shown with lower lock supports 20 that are located inside the
cylinders 16 of the housing 11. In this embodiment the linking
element 202 is a solid bar that can transfer compressive as well as
tensile loads. The locking actuator 26 rotates the leading lower
lock support 20A, which pushes on the linking element 202. The
linking element 202 in turn pushes and rotates the following lower
lock support 20B. The lower lock supports 20A and 20B engage the
upper lock supports 17 that are located inside the pistons 22
(shown in FIG. 14C). The rotation of the following lower lock
support 20B pulls the unlocking tether 212 into the housing 11
through the unlocking port 38. The unlocking tether 212 can be
tensioned away from the housing 11 to reverse the process and
unlock the implant 10K.
[0140] The use of tension and compression elements as described
above are not the only means for coordinating the controlled
locking and unlocking of the device. In FIG. 48 an alternative
embodiment of the implant 10L is shown wherein thread gears 226A
and 226B are used to both lock and unlock the lower lock supports
20 thus forming a combined linking and unlocking element. Threaded
gears 226A and 226B are mounted on a shaft 224 that is contained in
the base of the housing. The proximal end of shaft 224 has a keyed
head 228 that can protrude from or rest in the locking port 222. An
external tool (not shown) can interface with the keyed head 228 to
rotate it in either direction. Rotating the keyed head 228 will in
turn rotate the shaft 224 and the threaded gears 226A and 226B. The
threaded gears 226A and 226B transfer the force to the lower lock
supports 20 through the geared bottom face 220. In the embodiment
shown in FIG. 48 the threaded gear 226A is oriented opposite of the
threaded gear 226B. This allows rotation of the shaft 224 to rotate
the lower lock supports 20 in opposite directions relative to each
other. It is obvious to those schooled in the art that the threaded
gears 226A and 226B can be oriented in the same direction if it is
desired to rotate the lower lock supports 20 in the same direction.
In either case the shaft 224 can be rotated in one direction to
rotate the lower lock supports 20 in the locking direction, and the
shaft 224 can be rotated in the opposite direction to rotate the
lower lock supports 20 in the unlocking direction.
[0141] An unlocking tether as described herein can be engaged and
tensioned by any number of means including but not limited to
gripping the unlocking tether between articulating grips, a collet
or split ring clamp, crimping the unlocking tether to a tensioning
wire or rod and cutting the unlocking tether to disengage after
use, mounting a magnet on the proximal end 214 (FIG. 46A) of the
unlocking tether and engaging the magnet with a mating magnet
attached to a tensioning wire of rod, adding a female or male
thread to the proximal end 214 or the unlocking tether and engaging
it with a mating thread on the end of a tensioning rod or wire, or
providing a continuous unlocking tether all the way to the point
external to the body for tensioning and then cutting the unlocking
tether near the implant after use to disengage. It is obvious to
those schooled in the art that the unlocking tether can
alternatively be pushed or compressed rather than tensioned as long
as it is configured to rotate the lower lock supports 20A and B in
the unlock direction and deliver sufficient load without buckling
when pushed.
[0142] FIG. 49 illustrates an alternative embodiment of an implant
10M with a pushable unlocking tether 212a. In this embodiment,
unlocking tether 212a engages the proximal lower lock support 20B
to rotate it in the unlock direction when the unlocking tether 212a
is advanced towards the proximal lower lock support 20B. The link
202 transfers that rotation from the following lower lock support
20B to the leading lower lock support 20A. The link 202 contains
engagement pins 230, which extend into receiving slots 232 on the
lower lock supports 20A and 20B in order to transfer the lateral
movement of the link 202 into rotation of the lower lock supports
20A and 20B. In much the same way, the unlocking tether 212 can
contain an engaging pin (not shown) to extend into a receiving slot
(not shown) on the following lower lock support 20B to transfer the
lateral compressive force applied to the unlocking tether 212a into
rotation of the lower lock supports 20B. This is just one method
for attaching or engaging the unlocking tether 212 to the lower
lock support 20 the numerous methods previously described herein
for attaching or engaging the link 202 to the lower lock supports
20 can be used for attaching or engaging the tether 212 as
well.
[0143] One advantage to pushing the unlocking tether 212a to unlock
the implant 10M is that the method for engaging the unlocking
tether is simplified. Unlocking tether 212a, which is pushed to
unlock the implant 10M can be contained within the implant 10M and
a push rod (not shown) can be easily directed into the implant 10M
through the unlock port 216 to actuate the unlocking tether 212a
and unlock the implant 10M such that it can collapse. This
eliminates the need to attach to the unlocking tether 212a which is
required when the unlocking tether 212a is tensioned to unlock the
implant 10M.
[0144] FIGS. 50A-D illustrate an alternate embodiment of the
implant 10N embodying features of the invention. Similar to the
implant 110 as shown in FIGS. 13A and 13B, the top end plate 113 of
the implant 10N articulates relative to the distal piston 122A and
proximal piston 122B. The ends of the articulating top plate 113
have spherical projections 2001A and 20001B which are contained
within mating pockets 2002A and 2002B in the two pistons 122A and
122b. Split rings 2006A and 2006B are placed over the spherical
projections 2001A and 20001B and into the pistons 122A and 122B to
vertically constrain the articulating top plate 113 to the pistons.
This geometry provides articulation of the top plate 113 along not
only the long axis (the axis extending along the line 50C in FIG.
50C), as with the implant 110 shown in FIGS. 13A-B, but also
provides articulation in a side-to-side direction, which is an
advantage for providing congruence of the implant to the
intervertebral space. Thus, the articulating top plate 113 is
polyaxially movably coupled to the pistons 122A and 122B, allowing
the plate 113 to articulate about at least two axes.
[0145] Also shown in FIG. 50D are vertical constraints 2003A and
2003B which are attached to the distal piston 122A and proximal
piston 122B. These two constraints 2003A and 2003B fit inside
channels 2004A and 2004B in the housing 111. The top portion of the
channels 2004A and 2004B have a narrowed portion 2005A and 2005B
that prevent the vertical constraints 2003A and 2003B from
advancing out of the housing 111. In this manner these vertical
constraints 2003A and 2003B limit the maximum vertical movement of
the pistons 122A and 122B relative to the housing 111.
[0146] FIGS. 51A-B illustrate another alternative embodiment. FIGS.
51A-B illustrate an implant 10P that can have features similar to
features in the embodiments illustrated in FIGS. 13A, 14A-C, and
49. The implant 10P has the articulating top plate 113 similar to
that shown in FIG. 13A which pivots relative to the distal piston
122A and proximal piston 122B about a distal pivot pin 2101A and a
proximal pivot pin 2101B. The implant 10P has a distal piston 122A
and a proximal piston 122B. As with the pistons 222a and 222b shown
in FIGS. 14A-C, the pistons 122A and 122B can have internal upper
lock supports 217. Unlike implant 210, in the illustrated
embodiment, the pistons 122A and 122B do not rotate relative to the
housing 111 as is the case in the implant 210. Instead, lower lock
supports 20A and 20B similar to those shown in FIG. 49 rotate
relative to the housing 111 and the two pistons 122A and 122B to
lock the height of the expanded implant. In this manner, benefits
of several of the previously described embodiments are combined to
provide and implant 10P that can lock at different distal and
proximal heights.
[0147] FIGS. 52A-F illustrate an alternative embodiment of the
present invention, exemplified by implant 10R. In this embodiment,
implant 10R can include a distal piston top plate 2222 that can be
completely separate from a proximal piston top plate 2223. As shown
in FIGS. 52B-D, the two piston top plates 2222 and 2223 can each
expand to different heights relative to the housing 111. Thus, the
independently adjustable top plates and their respective pistons
provide a simple construct that can achieve variable expansion
similar to the articulating top plate 113 in implants 10N and
10P.
[0148] In some embodiments, the extendable members, such as pistons
122A and 122B, may be actuated by a common actuator such as a
single syringe or other pressurized fluid source but constrained as
described herein to rise to independent/different heights. Such
constraint may be provided by specific constraint means as
described, by a common top plate such as shown in FIG. 50D or a
combination thereof.
[0149] As shown in FIG. 52F, the implant 10R can include a proximal
lower lock support 20B that can have stepped support surfaces that
have shorter increments than the stepped support surfaces on a
distal lower lock support 20A. The mating stepped support surfaces
on the proximal upper lock support (not shown) in the proximal
piston 122B can also have shorter increments than the stepped
support surfaces on the upper lock support in the distal piston
122A. This variation in stepped support surface can be designed to
produce a specifically desired expanded height difference between
the expanded distal piston top plate 2222 and the expanded proximal
piston top plate 2223. In addition, the expanded height difference
can vary with the amount of expansion. This variation can be
valuable, for example, for creating lordotic congruence between the
implant 10R and the vertebral bodies as the amount of lordosis
required for proper congruence and spinal foraminal opening can
increase along with the increase in distance between the vertebral
bodies.
[0150] The implant 10R can also have vertical constraints 2005A and
2005B which can be attached to the housing 111. In the illustrated
embodiment, the vertical constraints 2005A and 2005B can prevent
wide portions 2003A and 2003B of the distal piston 122A and
proximal piston 122B from advancing out of the housing 111. In this
manner, these vertical constraints 2005A and 2005B can limit the
maximum vertical movement of the pistons 2222 and 2223 relative to
the housing 111.
[0151] FIG. 53 illustrates yet another alternative embodiment. As
shown in FIG. 53, an implant 10S can have a distal piston 122A that
can have both a horizontal vertebral engagement surface 2240 and an
angled vertebral engagement surface 2242, such that the distal
piston 122A can have a variation in vertebral engagement surface
angles. These variations in vertebral engagement surface angles can
be beneficial for providing even better congruence between the
implant 10S and the vertebral bodies when a lordotic or variable
height expansion is desired. The implant 10S can also have a
proximal piston 122B with a higher horizontal vertebral engagement
surface 2244 and a lower horizontal vertebral engagement surface
2246, which can also improve congruence between the implant 10S and
the vertebral bodies when a lordotic or variable height expansion
is desired. As will be recognized by a person of ordinary skill in
the art, any combination of these varied vertebral engagement
surfaces can be employed on either the distal piston 122A, the
proximal piston 122B, the articulating top plate 113 or the
posterior surface of the housing 111 to provide optimal vertebral
body congruency.
[0152] The features of the current invention have been described in
terms of an implant comprised of a pair of cylinder/piston/lock/and
related features, however it is obvious to those schooled in the
art that the described features can be included in an implant with
only a single set or more than two sets of these features.
[0153] A lateral cage implant, as illustrated for exemplary
embodiments of the present invention herein, is particularly
advantaged by the use of anchors as described herein because the
lateral approach to the spine is a long and narrow approach, which
limits the ability of the surgeon to use other instrumentation to
extend anchors from the cage (as can be done more readily, for
example, with an anterior approach where the access is not as
narrow). However, as will be appreciated by persons of ordinary
skill in the art, while particular, additional advantages may be
presented in connection with the lateral approach and cages
designed therefore, anchors according to embodiments of the present
invention are advantageous for any approach as they can produce the
required extension forces regardless of patient anatomy or other
restrictions on the use of alternative extension means by the
surgeon.
[0154] Elements of the description herein focused on the manner in
which the locking elements are configured to lock the implant in
extended configurations. Although this locking action resists the
forces placed on the implant that would tend to force it back into
a collapsed configuration, that is not the only force the locking
elements address. Once inserted between vertebral bodies the
implant is subject to lateral forces and torsion moments as well as
compressive forces. The locking features along with the other
elements of the invention are designed to resist all of these
forces to provide an implant that provides stable fixation and
distraction.
[0155] A partial or complete discectomy is usually performed prior
to the insertion of the spinal implant having features of the
invention between vertebral bodies. The implant is introduced in
its unexpanded state to enable it to be inserted posteriorly with
minimal trauma to the patient and risk of injury to nerve roots.
Once in place the implant can be expanded to provide both medial
and lateral spinal correction. The implant has an unexpanded height
of about 5 to about 15 mm, typically about 7 mm and is expandable
to at least 130% to about 180% of the unexpanded height. Typically
the implant is about 9 to about 15 mm wide, typically about 12 mm
wide and about 25 to about 55 mm long, typically about 35 mm long
to facilitate minimally invasive insertion and thereby minimize
trauma to the patient and risk of injury to nerve roots.
[0156] Additional details of the implant such as the attachment of
hydraulic lines and lines for transmission of a slurry or liquid
bone graft material, device and hydraulic fluid delivery
accessories and the like can be found in co-pending application
Ser. No. 11/535,432 filed on Sep. 26, 2006 and Ser. No. 11,692,800,
filed on Mar. 28, 2007, which are incorporated herein by
reference.
[0157] It will be appreciated that the implant, including its
various components should be formed of biocompatible, substantially
incompressible material such as PEEK or titanium, and preferably
type 6-4 titanium alloy or other suitable materials which will
allow for long-term deployment within a patient.
[0158] While the invention has been described in connection with
what are presently considered to be the most practical and certain
preferred embodiments, it is to be understood that the invention is
not limited to the disclosed embodiments and alternatives as set
forth above, but on the contrary is intended to cover various
modifications and equivalent arrangements included within the scope
of the following claims.
[0159] For example, while implants described herein are expanded by
hydraulic fluid, other expansion means may be employed. For
example, the screw mechanism described herein may be employed to
expand scissor jacks within the implant to engagement adjacent
vertebral surfaces. Further, the implant can be provided with load
or pressure sensors that register differential pressure and
pressure intensity exerted on the engaging surfaces of the SEC by
the patient's vertebrae end plates to generate corrective signals,
for example by computer control, that are used, e.g. by the surgeon
or by a computer-controlled mechanism to realign the patient's
spine. The invention may further include a system that makes these
adjustments, responsive to sensor signals, in real time and on a
continual basis, such that the shapes of the implant changes to
realign the patient's spine or mechanism. Preferably, such system
is contemplated for use in setting the positions of the pistons
during installation of the implant.
[0160] While particular forms of the invention have been
illustrated and described herein, it will be apparent that various
modifications and improvements can be made to the invention.
Additional details of the spinal implant devices may be found in
the patents and applications referenced herein. To the extent not
otherwise disclosed herein, materials and structure may be of
conventional design.
[0161] Moreover, individual features of embodiments of the
invention may be shown in some drawings and not in others, but
those skilled in the art will recognize that individual features of
one embodiment of the invention can be combined with any or all the
features of another embodiment. Accordingly, it is not intended
that the invention be limited to the specific embodiments
illustrated. It is therefore intended that this invention be
defined by the scope of the appended claims as broadly as the prior
art will permit.
[0162] Terms such as "element", "member", "component", "device",
"means", "portion", "section", "steps" and words of similar import
when used herein shall not be construed as invoking the provisions
of 35 U.S.C .sctn. 112(6) unless the following claims expressly use
the terms "means for" or "step for" followed by a particular
function without reference to a specific structure or a specific
action. All patents and all patent applications referred to above
are hereby incorporated by reference in their entirety.
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